Etching compound



Patented Mar. 12, 1935 UNITED STATES PATENT OFFICE ETCHING COMPOUND Frank Costa and Candide Munumer, New York, N. Y.

1 Claim.

Our invention is a compound which will quickly etch or engrave metal such as steel, iron, tin, zinc and silver and is intended primarily for use in making finger prints, but it is, of course, capable of use wherever a permanent record is desired.

The composition constituting our present invention consists of four ounces of water, one and one-fourth ounces of copper sulphate, one ounce of common salt, and one and one-half grams of gelatine. The water is heated and the gelatine is then dissolved in the water. Dry copper sulphate is mixed with the salt and this mixture is then dissolved in the gelatine solution, and when the solution has thoroughly cooled it will be ready for use.

When it is desired to make a finger print, some of the solution may be poured upon a pad and then the finger pressed upon thepad so as to take up some of the solution. The finger bearing the solution is then pressed upon a metal plate and when the solution has dried a permanent print of the finger will appear. If it be desired to engrave a specimen of handwriting upon a plate, an ordinary pen may be dipped into the solution and then the name or other matter may be written upon a metal plate just as though it were being written on paper. Care should be observed to avoid overloading the pen and, of course, it will be advisable to operate quickly in order to avoid corrosion of the pen.

The composition will be in liquid form and will retain its liquidity sothat it may be .very easily used, and whenapplied to a metal plate, the copper sulphate will effect a decolorization of the plate at those points where the compound touches the same. The salt and the copper sulphate will combine to engrave the plate so that the lines will be permanent. The gelatine in the compound will serve to impart some body thereto so that excessive spreading of the composition, when it is applied to a metal plate, will be avoided and the lines made thereby will be kept sharp and clear so that while the composition Will not assume a jelly-like form} it will not flow so freely as to defeat the purpose for which it is produced. 7

The composition is inexpensive and is eflicient in producing a permanent record. It may be used for branding tools and other articles so as to provide positive identification and thereby aid in recovering the articles if they should be stolen or misplaced.

Having thus described the invention, we

claim: a

An etching composition consisting of water four ounces, copper sulphate one and one-quarter ounces, salt one ounce, and gelatine one and one-half grams.

FRANK COSTA. EL. s.] CANDIDO MUNUMER. [L. s.] 

